A Bacterial Toxin That Hurts and Heals
Written by Tammy Chan
Edited by Cindy Ho
Jan 31, 2021
Edited by Cindy Ho
Jan 31, 2021
What is Staphylococcus aureus, and why even care about its toxins? Staphylococcus aureus is a type of bacteria found in the environment and in human areas such as skin and mucous membranes. Although S. aureus is often harmless, this bacteria can turn pathogenic, leading to various infections or inflammation. In the worst cases, sepsis can develop. Sepsis is a life-threatening medical emergency caused by the body’s extreme and overactive response to an infection; this severe response triggers a series of changes that can damage multiple organ systems. Without quick treatment, sepsis can lead to tissue damage, organ failure, and even death. To better understand S. aureus infections, let’s examine one of the bacterial toxins secreted by S. aureus– ∝-hemolysin.
Researchers from the Friedrich Schiller University Jena, Leibniz Institute on Aging – Fritz Lipmann Institute (FLI), and Jena University Hospital worked together with colleagues from Harvard Medical School and the University of Naples to study the human immune system’s molecular defenses against S. aureus infections. In a recent study, they discovered that the toxin, ∝-hemolysin, secreted by S. aureus did not just damage cells and tissues. It also encouraged specific immune cells to produce “specialised messenger substances that help to reduce inflammation and to promote tissue healing” (Bacterial toxin with healing effect).
For many S. aureus-mediated health problems such as skin infection and sepsis, the body initiates an inflammatory response in an attempt to protect itself. Regrettably, the molecular and cellular details behind such an action are largely unknown. Therefore, the effects of ∝-hemolysin on M2 macrophages caught the researchers’ attention. M2 macrophages are specific white blood cells that help resolve inflammation and play a key role in tissue repair. During the later stages of an inflammatory response, M2 macrophages contribute to the removal of damaged cell components and the bacterial cells killed earlier, as well as tissue regeneration.
Through experiments involving the selective activation of a seminal enzyme called 15-lipoxygenase-1 (15-LOX-1) and an animal model, the researchers demonstrated that ∝-hemolysin binds to specific receptor proteins on the surface of M2 macrophages. This binding stimulates the production of anti-inflammatory messenger substances such as resolvins and moresins, leading inflammation to settle down and for tissue to heal.
This interesting discovery about ∝-hemolysin could be significant for future treatments of inflammation and understanding the body’s response to pathogenic S. aureus. Anyone can develop an S. aureus infection, and individuals with a weakened immune system are particularly vulnerable. This is why the connection between ∝-hemolysin and healing should be further studied as we consider the possibility of a bacterial toxin that can contribute to healing.
Works Cited
Friedrich-Schiller-Universitaet Jena. "Bacterial toxin with healing effect." ScienceDaily. ScienceDaily, 13 October 2020. <www.sciencedaily.com/releases/2020/10/201013134304.htm>.
Jordan, Paul M., et al. “Staphylococcus Aureus-Derived α-Hemolysin Evokes Generation of Specialized Pro-Resolving Mediators Promoting Inflammation Resolution.” Cell Reports, 13 Oct. 2020. <www.cell.com/cell-reports/fulltext/S2211-1247(20)31236-5>.
Taylor TA, Unakal CG. Staphylococcus Aureus. [Updated 2020 Aug 23]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: <https://www.ncbi.nlm.nih.gov/books/NBK441868/>.
“Staphylococcus Aureus.” APIC. <apic.org/monthly_alerts/staphylococcus-aureus/>.